Proposed modification to the Zheng and Hirt fatigue model

Abstract

The Zheng and Hirt model describes the fatigue behavior of metals based on the tensile properties, thus eliminating the need for extensive fatigue crack propagation tests as required by other fatigue models. The model uses the fracture strength of the material based on a relationship. The predictability of the model was improved by incorporating into the equations the measured fracture strength of the material instead of the calculated value. An experimental investigation, consisting of both tension and fatigue testing on the 350WT category 5 steel, was performed to verify the proposed modification. The results showed that the modified model predicted the fatigue crack growth rates of the steel with a greater accuracy than the original model.